Now Click on Themes > Customize theme in your main admin and open the section titled: Money Options

Here you can choose to show a Currency Selector for customers to choose their preferred currency.This currency selector connects automatically to xe.com to give the most current exchange rates to customers.

You may choose a Money Format - Money with Currency should be used if you are using several options that use the Dollar symbol... For instance: CAD, USD, AUD

The Default Currency should always be the same as that used within the:Settings > General > Standards & Formats > Currency section of your admin.